Fixes to website code snippets for Web Scraping tutorial

If the code on the website is copied and pasted, it doesn't run, due to a couple of inconsistencies between the webpage and the code in the sample settings.py file. The differences are in BOT_NAME and  ITEM_PIPELINES. 

I changed the website to match the settings.py file (in Part 3 and Part 4, where settings.py is discussed), and  changed the command under "Manually Run the Scaper" (in Part 5) to match the new BOT_NAME.